Generator and Alternator

By Ship Electrical Engineer Ather Rizvi's Lecture on 

Generator and Alternator 

Fuel Lever Micro Switch on the governor (red in colour) is used to stop the generator from starting and stopping it in case of emergency. One of the few reasons for the generator not getting start is this lever being in the wrong position. It is one of the majour safties of the generator and has to be checked before the starting of the generator for its working.

Lube Oil cooler is used to maintain the temperature of the lube oil.
There are 4 different types of pressure switches

1. Lubeoil inlet low pressure Alarm.
2. Standby lubeoil inlet auto start.
3. Lubeoil inlet low pressure Switch.
4. Cool F.W. inlet low pressure Alarm.
5. Flywheel lever has two main functions.
6. To stop the generator in case of emergency.
7. Priming the genreator before starting or after changing the lube oil.

Drain tank is present on either side of the generator to accumulate the oil leaking from any part of the generator. It has a float switch which is responsible for intiating alarm when the tank is full.
Electrical Side of the Generator consists of Following parts:

1. Exciter
2. Alternator
3. Alternator is further devided into following parts:
4. Stator
5. Rotor
6. Diode
7. Armature
8. Heater to remove moisture and dampness from armature.
9. The control pannel consists of following main parts

A.C.B. (Air Circuit Breaker): Light of ACB turns on when the generator gets on load.
Bus Bars: Current generated enters the bus bars in three phases and then transmitted to the starter pannel. For a 3 phase generator there are 3 bus bars labled R, S, and T. In case of motor they are labled as U,V and W.

Reverse Power Relay: R.P.R. is used to prevent the generator converting into motor. It is tested by using synchronoscope. When two generators are run in parallel synchronoscope is used to synchronise their voltage, current and most importantly phase difference. For testing R.P.R. synchronometer is used to transmit voltage generated from say generator 1 to generator 2. If R.P.R. trips means that it is working properly. R.P.R. has a reset button which can be used to reset in case of a trip.

Synchronoscope: It is used to synchronise the phase difference and voltage developed by one or more generators in parallel. It is done by lowering the r.p.m using the governor and then synchronise the supply when the needle is at 0. In case of Auto it is all done by itself.

Voltage Regulator: It is used to increase or decrese the volatage to reach the desired amount. It can only increase or decrease small amount of voltage.

Preferential Trip: It is used to supply the current to the appliances.

Marine engineering paralleling of generators

Marine engineering paralleling of generators

• 1.  
• 2. IT IS THE ALLAH WHO SUBJECTED THE SEA TO YOU.THAT SHIP MAY SAIL THROUGH IT BY HIS COMMAND ,THAT YE MAY SEEK OF HIS BOUNTY,AND THAT YE MAY BE GRATEFUL (Al-Quran)
• 3. Marine Engineering Paralleling/Synchornizing of generators
• 4. Synchronizing or paralleling of generators Start the incoming generator Check the voltage and frequency of the generator. When the synchroscope will between 12 o clock to 5 o clock And synchronizing lamp revolve slowly clockwise. Close the air circuit breaker (ACB).
• 5. Note The incoming generator voltage and frequency must be greater then busbar voltage and frequency to prevent reverse power relay trip. Always close the ACB when the synchroscope is between 12 to 5’o clock.clockwise.
• 6. Author Introduction ZEESHAN AHMED , Marine Engineer . After doing FSc(pre-engineering) from PAF(fazaia) intermediate college Lahore cantt. I joined Pakistan Marine Academy and choose Marine engineering branch. Two years of training at academy (practical + theoretical) we learned a lot of thing like CNC (computerize numeric code), trained on various models (like control valve, solenoid valve, flow meter, refrigeration system, CPP propeller, Main engine model (TWO stroke), Boiler model (water tube) ……………………………….. in GEK (general engineering knowledge) lab, Mechanical and physics lab, Engineering workshop. ETC . After two years, we joined PNSC workshop for the training of ONE year Industrial training. That was also the golden time where we learnt a lot of things at different shops as well as onboard (repairing and watch keeping). I learn many thing on tanker E.g. MT Johar (learn how to dismantle turbine rotor from casing and what are the precautionary measurement while working on turbine, learn how to change the diaphragm(stationary blade) Plate type heat exchanger gasket change, shell and tube Cooler Anode replacement and (Cont.)
• 7. Introduction (cont.) cleaning of SALT WATER tubes etc.) , MT Swat (major thing which I learn in Swat is how to dismantle head of main unit and copper gasket replacement with a minor facing defect which is found during overhauling which is filled and faced by Belzona) , MT Lahore(About the DEAD MAN ALARM, Alpha lubricator for Cylinder Main Engine Unit, Pump operation and watch keeping), MT Quetta(Auto load sharing of Generator Set, MT Karachi (Dry washing of the main engine turbocharger with granules, water washing of IG Fan of Inert Gas system, sludge removal of from purifier(centrifuge) etc., . One thing I want to added is that the trend in ship building is more toward based on electronic and electrical application. So a marine engineer must strong in automation, instrumentation and control system. PLC (programmable and logic control) and SCADA (supervisory central access and data acquisition) are the upcoming technology that are using on modern ship. The latest engine of MAN B&W is based on Camless technology. Chain is removed ; fuel pump and exhaust valve actuation is control by hydraulic servo(lub) oil which is driven by Axial piston pump mounted on the Fly wheel. Regards, Z.A.
• 8. Author contact information zeetec4@yahoo/gmail/hotmail.com Social networking sites. Facebook: mariner46 Website: zeetec4.googlepages.com Any question and suggestion are welcome